Windows 8 may work well as a tablet OS, which seems to be the focus of your post. As far as a desktop OS, though, I'm gearing up for disappointment, given the reviews I've read elsewhere. For those of you who think the desktop is dead/dying/obsolete, no need to read any further...
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...for everyone else, I invite you to commiserate about what we'd like in a new version of Windows, and what we'll actually get. Here's my own take on it.
What I'd like to see in a new, desktop version of Windows:
- stability and security
- improved performance for common tasks (copying files, inserting and removing USB drives, browsing the list of installed programs, booting up, etc.)
- fixes to longtime annoyances
- noticeable, incremental improvements (that are indisputably improvements)
- the continuing ability to buy and download whichever version of Windows I'd like to buy, whether it be XP, Vista, 7, 8, etc. (without jumping through obscure "downgrade" process hoops)
- a subscription model for Windows. I'd like to be able to always obtain the latest version of Windows for a moderate fee ($40 a year?), and to receive incrementally-improved versions while I'm subscribed.
Unfortunately, I've lost hope that I'll ever get this from Microsoft. Here's what I wouldn't be surprised to get in Windows N (where N = 8, in this case):
- slower overall performance which requires hardware upgrades
- radical changes to the UI, in which Microsoft breaks as many things as it improves. (Windows N always has a few cool features which Windows N - 1 didn't have. Yet Windows N often breaks, slows down, or reduces the usability of many useful Windows N - 1 features.)
- deprecation of my favorite features (For example, as happy as I was that Windows 7 lets you set up and use the Quick Launch bar, I wouldn't be surprised if this handy feature was wholly missing in Windows 8, or in a Windows N from the near future.)
- a huge price tag, which is hard to justify unless I'm buying a new PC. (OK, a $40 Windows 8 upgrade departs from this negative expectation. However, I'm holding my breath to see what happens with this price point in the future.)
- elimination of consumers' ability to purchase older versions of Windows, as much as they may want them. (I want to retain the ability to to help friends upgrade their untimely-purchased PCs from Vista to Windows 7, whenever I come across those unfortunate devices.)

I'd argue that the last truly revolutionary version of Windows was Windows 95. In the subsequent 17 years, we've seen a stream of mostly minor and often inconsequential design changes in Windows – at its core, you've got the same old stuff: a start menu, a desktop with icons, taskbar at the bot...

As long as Google keeps making the right decision with each change they make to Chrome, people will love Chrome's infinite upgrades. However, if Google gets things wrong, an infinite-upgrade system could become Chrome's undoing. Few companies consistently make the right product-design decisions.
What if Windows Update had infinitely-upgraded the whole OS during the past 10 years? Imagine the horror of watching your beloved Windows XP machine as it slowly disfigured itself into Windows Vista. I bet the same power users (like me) who protested the phasing-out of XP would have fought to disable Windows Update (or considered Windows alternatives) in this alternate history. Instead, we were able to keep XP, wait out Vista, and give Microsoft a chance to get it right (or at least better) with Windows 7. Microsoft might not have had a second chance in an infinite-upgrade alternate timeline.
Infinite, mandatory upgrades reduce consumers' available choices. It'd probably be best for a company to compete against its products' old versions (and itself) than to make old versions unavailable and force annoyed customers to reconsider competitors' alternatives. There are good reasons why sites such as OldVersion.com exist. ( http://www.oldversion.com/about.php )
As an independent desktop-software developer, I plan on making my programs' old versions available for download indefinitely (with appropriate disclaimers and warnings for significant bugs). If I ever implement an infinite-upgrade system, I plan to make it easy for users to disable it on their own if desired. (I'd also give them the option of notifying me of this change, to help me become aware of their discontent and of missteps I may need to correct.)

One of the things I like most about Google's Chrome web browser is how often it is updated. But now that Chrome has rocketed through eleven versions in two and a half years, the thrill of seeing that version number increment has largely worn off. It seems they've picked off all the low hanging ...

A couple of months ago, the humble 8 GB SSD on my two-year-old Acer Aspire One netbook called it quits, from one day to the next. I tried reinstalling the OS, but data wouldn't stick to the drive anymore. That's another (anecdotal) data point for you.

As an early advocate of solid state hard drives … The State of Solid State Hard Drives (October 2009) Revisiting Solid State Hard Drives (October 2010) … I feel ethically and morally obligated to let you in on a dirty little secret I've discovered in the last two years of full time SSD owne...